Milk compositions and fatty acid profiles in two coastal odontocete species from the southwest Atlantic Ocean

ABSTRACT Lactation is a crucial reproductive stage in eutherian mammals and the most energetically and nutritionally expensive part of the life cycle. However, data on lactation parameters in cetaceans remain scattered and incomplete. In this paper, we present novel information on the nutritional compositions and fatty acid (FA) profiles of the milks of two small odontocete species that inhabit coastal waters of the southwest Atlantic Ocean: the endangered Franciscana dolphin ( Pontoporia blainvillei ) and the Burmeister's porpoise ( Phocoena spinipinnis ). Milk samples were collected from the fresh carcasses of two lactating females stranded in Argentina. The milk profiles of both species were consistent with existing knowledge on odontocetes worldwide, being characterised by low proportions of carbohydrates and high proportions of proteins and lipids. The FA profiles exhibited a predominance of long‐chain FAs (≥18 C), with monounsaturated FAs representing nearly 50% of the total FAs. In both species, the main FAs were 18:1n9 and 16:0, which are common FAs in coastal prey species in this region. These findings are particularly relevant for the conservation of Franciscana dolphins, which are at risk of extinction throughout their distribution range.